One of my biggest frustrations while performing surgery is having to work with certain anesthesia staff that don’t realize that the patient is not breathing. The problem is that they are focused too much on their instruments, not realizing what’s really happening until things start to go wrong.
During sleep, your muscles are relatively more relaxed. For modern humans, due to a combination of narrowed jaws, soft tissue crowding, inflammation and gravity, the airway becomes more narrow and more prone to obstructed breathing. This is the main theme in my book, Sleep Interrupted: A physician reveals the #1 reason why so many of us are sick and tired.
Once in the operating room last week, I performed a drug-induced sleep endoscopy (DISE) procedure. This is when I look at the airway with a camera while the patient is in deep sleep using intravenous propofol, but still breathing regularly. If you give too much propofol, breathing stops entirely since there’s no signal from the brain to breathe. This is called a central apnea. What I typically see is called an obstructive apnea, where the blockage occurs at different areas of the throat, while the patient is trying to inhale. However, if the patient has 100% oxygen running, then it takes longer for the levels on the monitor to drop when the patient stops breathing, whether from central or obstructive apneas.
However, once in a while, I see that the patient is clearly obstructing and straining to breathe, but since the oxygen level on the monitor is in the high 90s, and there’s some carbon dioxide (CO2) coming out the the lungs, the anesthesiologist thinks that everything seems fine. However, if this goes on for too long, the oxygen level will drop quickly since the patient is struggling to breathe through an opening the size of a small straw. Having a little bit of CO2 coming out is not ideal. Once the oxygen level begins to drop to dangerous levels, only then does the anesthesiologist quickly take measures to have the patient breathe better again.
You can even see only partial degrees of breathing blockage with the patient straining to breathe, but the oxygen level will be fine. This is equivalent to what’s called flow limitation in sleep studies, where you have flattening of the typical rounded nasal airflow tracings that are not severe enough to be called apneas or hypopneas. Flow limitation can oftentimes lead to brain wave arousals from deep top lighter stages of sleep. This is what’s shown in Dr. Guilleminault’s classic article on upper airway resistance syndrome (UARS).
What I do to prevent this situation is to carefully watch the patient’s breathing patterns, rather than look at the monitors. I will thrust the jaw forward, like what a mandibular advancement device does for sleep apnea, but much more aggressively. Rarely, even this doesn’t work and we have to ventilate with a face mask using positive pressure.
I don’t blame anesthesiologists since they are not used to keeping patients in a relatively lighter state of anesthesia compared to what they’re normally used to doing. With good education, communication and teamwork, these procedures a very safe. If you’re not obstructing, there’s no reason to give 100% oxygen; even room air will work fine. If you’re obstructed, no air will get through at all.
What’s I’ve learned from doing hundreds of these sleep endoscopies recently is that almost everyone with upper airway resistance syndrome will have significant (and sometimes severe) obstruction at one or more levels. You can read my publication here describing sleep endoscopy findings in people who don’t officially have sleep apnea (AHI < 5).
The main gist of this article is that sometimes, thinking that oxygen will help you to breathe better is a myth. There are a number of other factors to consider when trying to breathe optimally. However, the most important consideration to good breathing is to have completely unobstructed breathing, during the daytime and especially when you’re sleeping. Once this is accomplished, then you can address the quality of the air (including the oxygen content), and what your body does with the oxygen once it’s received into the lungs.